A program executed by a control apparatus such as a programmable controller included in an FA (Factory Automation) system is described, in general, using symbols in a circuit diagram format (hereafter referred to as ladder program) by a relay symbolic language based on an idea of a relay control circuit. Besides, the program is sometimes described using symbols in formats such as an FB (Function Block), an FBD (Function Block Diagram), and an SFC (Sequential Function Chart). Creation of the program described using such symbols is graphically performed in an information processing apparatus using a program for program editing called an engineering tool.
In an engineering tool of a general control apparatus, a program described using symbols is edited using a mouse and a keyboard. For example, when a program constituent element such as a circuit symbol or a connection line is added to a ladder program, on an editing screen for editing a program, editing of the program is enabled by repeating, using the mouse or the keyboard, after designating a position where the program constituent element is to be added, selecting the program constituent element desired to be added. When operation other than the addition of the program constituent element is performed, editing of the program is enabled also by repeating processing for designating a target of operation and selecting processing desired to be executed (hereinafter referred to as command).
On the other hand, in recent years, an input technology using an information processing apparatus which is equipped with a touch panel input function (hereinafter referred to as a tablet terminal) is actively performed. When an engineering tool is used in the tablet terminal, a method of enabling editing of a program by treating operation for touching a finger on the touch panel equivalently to operation for designating a target of operation with a mouse cursor and pressing a mouse button is a general method.